The present invention relates to a pliers-type tool with two handles which are operatively connected with two carrier members adapted at one end to carry or to embody a working jaw. The carrier members may be mounted on a parallel mechanism for mutual approachment in a parallel disposition during a closing movement, and/or the two handles may be interconnected with the aid of a connecting link hinged to each of them.
Pliers-type tools with a parallel approach movement of the jaw carriers are used when some special circumstance makes a scissors-like pivotal movement of the jaws inappropriate, or impossible. Such a circumstance may be e.g. the use of working jaws comprising a plurality of intermeshing webs, as shown in FIG. 4, unless the jaws were oriented so that a treated object had to be inserted from the side of the tool. It is however often preferred to be able to insert a treated object into a pliers-type tool from the front end of the tool.
In any pliers-type tool there extends a force transmitting path between a location on the tool where an external operating or supporting force is applied (e.g. the part of the handles where the user grips them) and the associated jaw (where the force is transferred to an article held between the two jaws). The force transmitting path is defined by those interconnected and cooperating structural parts (inclusive of possible pivot pins) which lie between the two terminal points of the path. It is known, e.g. according to the U.S. Pat. No. 4,381,661 (henceforth referred to as "the said patent") to arrange a resilient element or member somewhere in the force transmitting path so that e.g. a greater working force may be applied to larger articles than to smaller ones.
A typical field of application of the tools for the aforesaid kind is crimping of ferrules on the ends of electrical conductors. To prevent incomplete crimping due to the jaws having been opened before they have reached their final closed position, it is customary to provide such tools with a motion completion compelling mechanism which allows opening of the jaws only after a final closed position has been reached. Such a mechanism, shown e.g. in FIG. 1 in said patent, may comprise an arcuate row of teeth and a ratchet pawl engaging therewith.
To enable compensation of possible inaccuracies in production and/or of wear effects after some time of use, one of the pivot pins, e.g. in the force transmission path, may have an eccentric central part, so that by selecting and securing an appropriate rotational position of such a pin, said inaccuracies and/or wear effects may be compensated (see FIG. 7 in said patent).
It is an object of the present invention, in a first aspect thereof, to provide a tool of the kind specified which has short constructional length and into which a treated object may be inserted from the front end, i.e. in the longitudinal direction of the carrier members.
Another object of the present invention is to provide such a tool with a motion completion compelling mechanism regardless of the presence or not of a connecting link.
Yet another object of the present invention, in a second aspect thereof, is to provide in a tool with two jaw carrier members and two handles an interposed resilient member not affecting the force transmitting path and/or filling the function to compensate for possible production inaccuracies of wear effects.
In accordance with the present invention, in a first aspect thereof, a pliers-type tool comprises, in combination, a first and a second longitudinal carrier member, each having a first end adapted to carry or to embody a working jaw, and an opposite second end, and both provided, adjacent each said end, with a mounting opening, and a parallel mechanism for carrying the said carrier members and allowing them to approach, in a closing movement, one another in parallel disposition. The parallel mechanism comprises, in a manner known per se, a first and a second guide lever means, each having a circular central mounting opening and two equidistantly therefrom spaced peripheral mounting openings, the two guide lever means being in cross-wise disposition pivotally connected one with another by a central pivot pin means in said central mounting openings. Four peripheral pivot pins means are mounted in said mounting openings in the carrier members and in said peripheral mounting openings in the guide lever means to pivotally attach the carrier members to the guide lever means, the mounting openings at the second ends of the carrier members, or the thereto adjacent peripheral mounting openings in the guide lever means, being elongated in the longitudinal direction of the carrier member to allow movement of the respective pivot pin means in said direction, all the other mounting openings being circular. The tool comprises further a first handle rigidly connected with one of the parts first guide level means, and first carrier member, to define a unit or a tool body therewith. A second handle is pivotally connected to said tool body, and via a force transmitting member is operatively connected with the second carrier member. A driving link embodies said force transmitting member and is pivotally connected to the second handle and to the second carrier member.
In accordance with a second aspect of the present invention, a pliers-type tool comprises, in combination, a first and a second carrier member, each one adapted to carry or to embody a working jaw, and to approach one the other in a closing movement and a first and a second handle, operatively connected with the first and the second carrier member respectively and approachable, in a closing movement, one to another to produce said closing movement of the carrier members, each handle having a first free end and an opposite second end for connection to the respective carrier member. A connecting link pivotally connects the first and the second handle and has a first hinge point for attachment of the first handle and a second hinge point, spaced from the first one, for attachment of the second handle and a resilient member is at a location spaced from said first hinge point interposed between the said connecting link or a part rigidly connected therewith, and is positioned and dimensioned so as to be, at least in a final phase of said closing movement of the handles, compressed by the two parts between which it is interposed.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be made to the accompanying drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention .